1. Technical Field of the Invention
The present invention relates to novel cosmetic or dermatological compositions comprising at least one dihydroxyacetone (hereinafter sometimes "DHA") derivative. More especially, this invention relates to novel artificial or self-tanning compositions having improved activity and stability.
The present invention also relates to novel dihydroxyacetone derivatives, per se.
2. Description of the Prior Art
It is known to this art that dihydroxyacetone, or DHA, is a particularly advantageous compound which is commonly employed in the cosmetics field as an agent for the artificial tanning of the skin. When topically applied to human skin, in particular to the face, it elicits a tanning or browning effect, the appearance of which is similar to that which may result from prolonged exposure to the sun (natural tan) or under a UV lamp. Such a use, moreover, presents the advantage of totally avoiding the risks of skin reaction which are generally associated with the aforesaid prolonged exposures (erythema, burning, loss of elasticity, appearance of wrinkles, premature aging of the skin, and the like).
However, the use of DHA also presents many drawbacks. Essentially, these appear during storage of compositions containing DHA and are quite incompatible with the expectation of the consumer. Thus, DHA has an annoying tendency, which is more or less pronounced depending on the nature of the medium in which it is formulated, to degrade over time. This degradation generally is reflected over time by an undesirable yellowing of the compositions containing same. It also occurs that, over time, such compositions develop a nauseating odor. Lastly, the pH of compositions containing DHA decreases over time, in the long run rendering same incompatible for use in topical applications (pH of the skin in the region of 5.5).
The result of the above phenomena, encountered during the period of storage of compositions containing DHA, is that the activity of the DHA, and in particular its ability to color the skin, is greatly decreased when these compositions are applied to the skin. Thus, the intensity of the coloration obtained on the skin and/or the speed with which this coloration develops may appear as still insufficient. It is also known that the content of DHA on the skin is not perfect.
In order to increase the speed of appearance of the coloration due to DHA or the resistance of the latter over time, it has been attempted to combine DHA with other substances. Thus, EP-A-547,864 describes providing DHA in the presence of an amino acid and a silicone, the DHA and the amino acid being stored before application to the skin in separate compartments. Too, WO-A-94/04,130 describes a device for providing DHA at the same time as a primary amine, these two compounds also being stored in separate compartments.
However, these devices do not entirely solve the problems of yellowing, of odor and of instability due to storage of the DHA.